The prestige number is the highest of two possible values (as shown in the ring\'s party interface):

Your current progress.
Your previous progress.
The higher this number is, the more prestige XP you will get (just like floor XP).

Example:
Runescape: You have done floor 1 to 5. As you begin floor 6, you will see in your ring interface that your current progress is 5. Once you complete floor 6, you will get prestige 6 because that\'s your new current progress. However, if you now do floor 6 again, you will not get prestige at all. If you are unable to proceed to room 7, then you should leave your party and press "Reset" in your ring interface. When picking floors, the floors which you have already done, and therefore are unable to get prestige on again, are the ones with checkmarks on them. In the picture above, the player in game(runescape money) still needs to do floors 1 to 8 but has floors 9+ checkmarked.

What happens when we reset?

All floors will be set to "undone" so that you will get prestige XP from all of them. Your prestige level(runescape gold) gets locked at your current progress. Example when you reset prestige: With the example from above, you have prestige 6. You reset and start again from floor 1. You will still have prestige 6 when you do floor 1, 2, 3, 4, 5 and 6. However, when you have done all floors from 1 to 6 and go to floor 7, then your prestige will be 7.